Richardson's fifth 3-pointer gave him 17 points and handed a decisive lead to the Magic, who finished the contest on an 11-0 run and claimed the first contest of their Eastern Conference quarterfinal series against the third-seeded Pacers.
The all-star center underwent season-ending back surgery last week and is out for the playoffs.
David West scored 19 points and grabbed nine rebounds for the Pacers, who didn't score in the final 4 minutes and missed nine straight shots down the stretch.
Danny Granger added 17 points and eight boards, but was whistled for traveling in the game's waning seconds.
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